New fiber light patterns will shatter a ‘bandwidth ceiling’

Holograms can be used to gain higher data rates in fiber, increasing bandwidth 100 times, scientists say

New fiber light patterns will shatter a ‘bandwidth ceiling’
Credit: Wits

Traditional fiber-optic communication sends data using just one light pattern. That’s fine, but it means the amount of bandwidth that a fiber strand can deliver is limited. If you could add more light patterns alongside the initial one, you could increase the bit rate, some scientists say.

By bundling more information-containing light arrangements into a fiber, you could theoretically increase bandwidth.

And scientists think they might have figured out how to do it. They say they are ready to crack what they call a “bandwidth ceiling.”

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Their system is to add more light patterns to the transmission using holography.

Over 100 patterns of light could be packed into one optical fiber link, University of the Witwatersrand (Wits) in Johannesburg says in a press release. And by doing so, it creates massive amounts of extra space for data, it believes.

Wits performed the work along with the Council for Scientific and Industrial Research (CSIR) in South Africa. The findings are published in scientific journal Nature.

Bandwidth could be increased 100 times with the new method.

Using holograms to increase bandwidth

Traditionally, light is manipulated anyway in order to relay data, the scientists explain. The “amplitude, phase, polarization, color and frequency of the light” are all modulated. But light also has a pattern, they say.

That pattern is related to “the intensity distribution of the light,” in a similar way to how light “looks on a camera or a screen,” is how they explain it. And those patterns “can be used to encode information” because they are unique.

The researchers, who are from South Africa and Tunisia, are using digital holograms that they write to liquid crystal display screens (LCDs). The wavelength-independent holograms are encoded with about 100 patterns using numerous colors.

“One hundred holograms were combined into a single, complex hologram," they say. "Moreover, each sub-hologram was individually tailored to correct for any optical aberrations due to the color difference, angular offset and so on.”

The light from the hologram is then sent over the channel in “free space” or in a fiber network.

When it gets to the destination, all of the patterns are then viewed at the same time by a detector. The result is that the 100 unique patterns create the 100-times increase in bandwidth, they claim.

Increase information in light, increase bit rate

The premise is basically that by packing more information in light, you increase bit rate.

Additionally, by using multiple wavelengths, as they do, you actually need fewer patterns to create the channels. The scientists were able to use 35 patterns across three wavelengths to obtain 105 channels.

But in any case, 10 patterns, say, which make up 10 new channels, create a 10-times increase in bandwidth.

“Although our scheme is a proof of concept, it provides a useful basis for increasing the capacity of future optical communication systems. Our results offer a route to higher bit rates for next-generation optical networks,” the scientists say. It’s an alternative source “that will be able to take over where traditional optical communications systems are likely to fail in future.”

“This is the highest number of patterns created and detected on such a device to date, far exceeding the previous state-of-the-art,” says Professor Andrew Forbes, of Wits.

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